1. Field of the Invention
The present invention relates to the structure of a circuit section in a multi-switch device to be used as a power switch for switching from one air volume to another in a ventilation fan for example.
2. Description of the Related Art
As a conventional power switch to be used for switching from one air volume to another in a ventilation fan for example there mainly is used a push-button switch of an interlocking type having plural push-buttons. By depressing these push-buttons selectively it is made possible to switch over among functions such as OFF (Reset) open (opening of flaps), Weak Wind, Medium Wind, and Strong Wind.
In such a conventional multi-push-button switch, an independent switch circuit section is formed for each push-button and external connection terminals are provided for each such switch circuit section. Further, connectors for wiring to a power supply and a ventilation fan are connected to the external connection terminals.
Such a conventional switch device is mainly composed of a housing which is formed generally in a box shape using an insulating material such as a synthetic resin and in which are formed plural receptacle portions, slide members disposed respectively in the receptacle portions vertically slidably, movable contacts formed of an electrically conductive metallic material and held by the slide members respectively, fixed contacts also formed of an electrically conductive metallic material and disposed in the receptacle portions respectively, the fixed contacts being put in sliding contact with and disengagement from the movable contacts to turn ON or OFF a circuit, return springs for restoring the slide members lying in depressed positions to initial positions respectively at the time of an interlocking operation, and interlocking cams for interlocking the slide members.
According to the construction of the above switch circuit section, the fixed contact disposed in each receptacle portion in the housing has a contact surface located in an ascending/descending direction of the associated slide member, the associated movable contact which comes into sliding contact with the fixed contact is held by the slide member so as to come into sliding contact with the contact surface of the fixed contact. That is, contact portions are put in sliding contact with each other in the ascending/descending direction of the slide member.
In the above structure of the conventional switch device, however, an independent switch circuit section is formed for each push-button, external connection terminals are provided for each switch circuit section, and connectors for wiring to a power supply and a ventilation fan are connected respectively to the external connection terminals. Thus, since connectors are needed for each switch circuit, there arises the problem that the working efficiency at installation is poor.
Moreover, in each of the above switch circuit sections, the contact surface of the fixed contact is disposed in the ascending/descending direction of the slide member, and the movable contact for sliding contact with the fixed contact is also formed in the ascending/descending direction of the slide member so as to come into sliding contact with the contact surface of the fixed contact, thus requiring a certain distance for the sliding contact in the operating (ascending/descending) direction of the slide member. As a result, the depth of the housing becomes large and hence there arises the problem that the reduction of size is difficult.
Accordingly, it is an object of the present invention to solve the above-mentioned problems and provide a structure of a multi-switch device of an interlocking type having plural push-buttons wherein external connection terminals of the switch device can be connected using a single connector and the reduction of switch size can be attained while ensuring a high contact reliability of contact portions.
For solving the above-mentioned problems, according to the first means adopted in the present invention there is provided a switch device comprising a housing having a plurality of receptacle portions; a plurality of fixed contacts disposed in the receptacle portions; a plurality of slide members which hold movable contacts, the movable contacts being adapted to move into contact with and away from the fixed contacts, and which are disposed vertically movably in the receptacle portions; and a plurality of connecting terminals drawn out from the from the fixed contacts and projected to the exterior of the housing, wherein a connecting groove for connecting together the plural receptacle portions is formed in the housing, the plural fixed contacts and connecting terminals are fixed integrally to a single wafer and are arranged on one and same plane, and the wafer is engaged with the connecting groove formed in the housing, thereby allowing the plural fixed contacts to be disposed within the receptacle portions.
According to the second means adopted in the present invention, the connecting groove formed in the housing is formed in a direction orthogonal to an ascending/descending direction of the slide members, the fixed contacts on the wafer engaged with the connecting groove are disposed on inside bottoms of the receptacle portions so that contact surfaces thereof lie in a direction orthogonal to the ascending/descending direction of the slide members, and the movable contacts and the fixed contacts are arranged in the ascending/descending direction of the slide members.
According to the third means adopted in the present invention, the slide members are each formed with a holding portion for holding the associated movable contact, and the movable contact is held in the holding portion in an obliquely inclined state with respect to the contact surface of the associated fixed contact.
According to the fourth means adopted in the present invention, the movable contacts are each formed with a convex projection and a chip-like contact portion both on the surface thereof opposed to the contact surface of the associated fixed contact, and while the associated slide member moves vertically, the convex projection first comes into abutment against the contact surface of the fixed contact and thereafter the chip-like contact portion comes into abutment against the contact surface of the fixed contact.
According to the fifth means adopted in the present invention, a spring member for urging the movable contact in a direction of abutment against the contact surface of the fixed contact is provided in the holding portion of each of the slide members, the spring member being constituted by a hand-drum-shaped coiled spring.